Artificial posterior tooth for the human teeth

ABSTRACT

The present invention concerns an artificial posterior tooth, namely a large and small posterior tooth for the upper and lower human jaw, the occlusal surface of which has at least one buccal cusp 6 and at least one palatal cusp 5, between which a longitudinal fissure 7 runs in the longitudinal direction of the tooth, the buccal cusp 6 of the posterior teeth of the lower jaw engaging in the fissure in the posterior teeth of the upper jaw and the palatal cusp 5 of the posterior teeth of the upper jaw engaging in the longitudinal fissure in the posterior teeth of the lower jaw. The longitudinal fissures 7 and the palatal/lingual cusps 5 and buccal cusps 6, respectively, of the posterior teeth 34 to 37 and 24 to 27 are adapted to one another such that, in the region of the longitudinal fissures 7, at least one rest zone 11 is formed in which there is a punctiform contact in the closed position of the posterior teeth 34 to 37 and 24 to 27, respectively.

FIELD OF THE INVENTION

The present invention concerns an artificial posterior tooth, namely alarge or small posterior tooth for the upper and lower human jaw, theocclusal surface of which has at least one buccal cusp and at least onepalatal or lingual cusp, respectively, between which a longitudinalfissure runs in the longitudinal direction of the tooth, the buccal cuspof the posterior teeth of the lower jaw engaging in the fissusre in theposterior teeth of the upper jaw and the palatal cusp of the posteriorteeth or the upper jaw engaging in the longitudinal fissure in theposterior teeth of the lower jaw.

BACKGROUND OF THE INVENTION

Artificial posterior teeth of this type are known. In the case ofindustrially produced artificial posterior teeth, however, the occlusalsurface is only poorly developed and in the closed position a planiformcontact region is present between the teeth lying on top of one another.This results in a stamp-like action of the teeth against one another,causing the teeth to adhere during mastication. This adhesion betweenthe teeth leads to poor masticatory properties of the denture formedfront the artificial teeth, with the occurrence, in particular, of theso-called "teeth chattering" during mastication. Moreover, in the caseof the known artificial, industrially produced teeth, the occlusalsurfaces do not interlock satisfactorily As a result, a manual finishingoperation is always necessary. Also, the planiform contact region in theclosed position of the teeth leads to unfavourable loading of theperiodontium.

The object of the present invention is to improve artificial posteriorteeth of the type described at the outset such that the masticatoryproperties and the support in the inserted state are improved and alsofavourable force distribution in the periodontium is achieved. Inaddition, the intention is to obtain a simplified alignment of the teethfor the production of the artificial denture.

SUMMARY OF THE INVENTION

The present object is essentially achieved in that the longitudinalfissures and the palatal/lingual cusps and buccal cusps, respectively,of the posterior teeth are adapted to one another such that, in theregion of the longitudinal fissures, at least one rest zone is formed inwhich there is a punctiform contact in the closed position of theposterior teeth. Through the production of a punctiform contact inconjunction with the existing furrowed cusp structure, a stamping actionis avoided, as a result of which improved masticatory properties areachieved. Arranging, according to the invention, the rest zones on thelongitudinal axis of the teeth leads to the force transmission alsobeing on the longitudinal axis of the teeth, as a result of which theperiodontium is spared undue stress. In the case of the prosthesesproduced using the posterior tooth according to the invention, thedynamics are thus enhanced and the masticatory mechanism relieved since,in an advantageous manner, the rest zones are formed over a wide area.

Furthermore, the present invention consists in forming in each case oneor more food discharge grooves in the occlusal surface of the teeth,which grooves lead to the outside via the edge of the respective toothbody. It is particularly expedient here if the food discharge groovesstart in the rest zones, at the deepest point thereof. Nevertheless, theformation of food discharge grooves is also expedient without thepresence of rest zones. Food discharge grooves of this type are notpresent in the case of the known artificial teeth, rather the lattermerely have faint traces of grooves which are not suitable for carryingoff the mashed food resulting during mastication to the outside. Bymeans of the food discharge grooves according to the invention, uniformdisintegration of the food is achieved and there is no accumulation andno instability. Moreover, the periodontium is thereby spared unduestress.

A further aspect of the present invention consists in formingpositive-locking elements on the opposite lateral surfaces of theposterior teeth, which positive-locking elements correspond in apositive-looking manner with the respectively opposite positive-lockingelements of the neighbouring tooth. This brings about an interlocking ofthe posterior teeth with respect to one another which makes it possibleto construct the lower or upper jaw comprising artificial posteriorteeth more easily, in denture production. Moreover, an unambiguousassignment and precise alignment of the teeth with respect to oneanother thereby results. In addition, the interlocking elements servefor mutual support and force transmission. The formation of theinterlocking elements on the lateral surfaces is also independent of theocclusal surface being designed with rest zones and/or with fooddischarge grooves.

By means of the masticatory-surface design according to the invention,it is possible to use the posterior teeth with their interlocking systemin a number of ways. The masticatory-surface relief according to theinvention allows the function of the posterior teeth with their cusps,rest zones and food discharge grooves to form a unit sic!. As a resultof this system, the tooth according to the invention has multifunctionalusability. In this regard, the concept according to the invention allowsteeth to occlude individually with respect to one another or to occludein each case with two teeth, upon interdigitation of the teeth.

Advantageous embodiments of the invention are contained in thesubclaims. The invention is explained in greater detail with the aid ofthe exemplary embodiments illustrated in the accompanying drawings, inwhich:

FIG. 1 shows a plan view of the occlusal surface of the posterior teethof the upper jaw,

FIG. 2 shows a plan view of the occlusal surface of the posterior teethof the lower jaw,

FIG. 3 shows a buccal view of the teeth according to FIG. 1,

FIG. 4 shows a palatal view of the posterior teeth according to FIG. 1,

FIG. 5 shows a lingual view of the posterior teeth according to FIG. 2,

FIG. 6 shows a buccal view of the posterior teeth according to FIG. 2,

FIG. 7 shows a lingual view of the posterior teeth according to FIG. 1and FIG. 2 in the closed position in an arrangement according to theinvention,

FIG. 8 a shows a lingual view of the posterior teeth according to FIG. 1and FIG. 2 in a second arrangement according to the invention,

FIG. 9 shows a section through a posterior tooth (24) in the region ofthe rest zones and

FIG. 10 shows a view of a rest zone region.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1 the plan view of the small and large posterior teeth of theupper jaw in the second quadrant, that is to say the small posteriorteeth 24, 25 and the large posterior teeth 26, 27 of the upper jaw, isillustrated The numbering shown corresponds to the numbering which iscustomary in dentistry for numbering the teeth of the upper and lowerjaw. Thus, in each case the occlusal surface of each individual toothcan be seen in this FIG. 1. Each of the large and small posterior teethhas, in its occlusal surface 1, 2, 3, 4, at least one or two palatalcusps 5, respectively, and at least one or two buccal cusps 6,respectively. The small posterior teeth 24, 25 preferably possess twocusps 5, 6 each. The large posterior teeth 26, 27 possess buccally twoapproximately equal-sized cusps 6 and palatally one large cusp 5 whichis mesial and on e smaller cusp 5 which is distal. Between the palatalcusps 5 and the buccal cusps 6 there is formed a longitudinal fissure(furrow) 7. In FIG. 1 the reference numeral 8 denotes the palatal toothridge and the reference nuneral 9 denotes the buccaal tooth ridge.According to the invention, rest zones 11 are formed within thelongitudinal fissure 7 in each of the teeth 24, 25, 26, 27. Thedistinctive feature of these rest zones 11 is that the supporting cuspsof the antagonist (the opposing tooth of the lower jaw), that is to saythe buccal cusps of the lower jaw, see FIG. 6, bear in these rest zoneswith point contact in the closed position of the upper and lower jaw andin the remaining region of the occlusal surfaces 1, 2, 3, 4 there is notouching contact.

The rest zones 11 each have a plurality of contact regions 13, it beingpossible for there to be a point contact on the cusps of the antagonistin each contact region in the closed position The contact regions 13have approximately the outline contour of an onion, i.e. they possess abulbous central region 14 adjoined by a tapering top region 15. Thesurface of the contact regions 13 is toroidal-shaped, and, seen incross-section both in the longitudinal direction X--X and in the Y--Ydirection perpendicular thereto, a convex sectional contour is formed.In FIG. 9 an individual contact region is illustrated. The contactregions 13 butt against one another by the base 16 of the central region14, so that between them fissures 17 are formed which run out towardsthe tooth edge.

The supporting cusps of the antagonist thus find support over a widearea in the rest zone, i.e. a corresponding clearance is present aroundthe punctiform contact region. As a result, the entire masticatorymechanism is relieved and sufficient freedom is thereby brought about inthe region of the posterior teeth on all excursions of the lower jaw. Inorder to ensure this punctiforn contact, a furrowed cusp structure ispresent according to the invention, the cusps being convex-shaped. As isrevealed in FIG. 1, these rest zones 11 are formed differently in termsof size and position in the individual posterior teeth 24 to 27. In thecase of the two small posterior teeth 24, 25, in each case merely onerest zone 11 is provided which is preferably situated in the mesialridge region of the tooth. This rest zone 11 comprises two contactregions 13 which are arranged in such a way that the longitudinal axisX--X runs somewhat perpendicular to the longitudinal fissure 7. The twolarge posterior teeth 26, 27 have two rest zones 11 which are spaced inthe longitudinal direction, one smaller rest zone 11 being located inthe mesial ridge region and one larger rest zone 11 being offsetdistally with respect to the tooth centre. Here, the larger rest zone 11comprises four contact regions 13, three of which are approximatelyequal-sized and larger than the fourth contact region. The four contactregions 13 are arranged in the shape of a star, the longitudinal axesX--X of the two respectively mutually opposite contact regions 13running obliquely with respect to the longitudinal fissure 7, and thesmaller contact region 13 being located approximately in the toothcentre. The small rest zone 11 comprises two contact regions 13 whichare arranged approximately in correspondence with that of the premolarsbut have smaller dimensions than these. The smaller rest zones 11 haveabout a width of approximately 0.17 cm, and the larger rest zones 11have about a width of approximately 0.24 cm.

In FIG. 2 the small posterior teeth 34, 35 and the large posterior teeth36, 37 in the third quadrant of the lower human jaw are illustrated, thenumbering of the teeth again corresponding, in this case too, to thenumbering of the teeth of the lower jaw which is customary in dentistry.In FIG. 2, identical tooth features to those in FIG. 1 are given thesame reference numerals As already stated, in the case of the teeth 34to 37 of the lower jaw, the buccal cusps 6 form the occlusion-fixingcusps and engage in the longitudinal fissure 7 in the respectiveantagonists of the upper jaw. In contrast, the occlusion-fixing palatalcusps 5 of the teeth 24 to 27 of the upper jaw engage in thelongitudinal fissure 7 in their respective antagonist in the lower jaw.

As is evident from FIG. 2, in each case one rest zone 11 is formed inthe teeth 34 to 37 of the lower jaw. Here, the rest zones 11 in thesmall posterior teeth 34, 35 are situated in the distal region, whereasthe rest zones 11 in the large posterior teeth 36, 37 are formedapproximately in the tooth centre in the occlusal surface of the teeth36, 37, In the case of the teeth 34 to 37 of the lower jaw, too, thelingual cusps 5 and the buccal cusps 6 are convex-shaped. The flankangle of the cusps 5, 6 is 20 to 30° here, thus ensuring a punctiformcontact in the respective antagonist in the region of the longitudinalfissure 7 and there in the respective contact regions 13.

The small posterior teeth 34, 35 are preferably formed in such a waythat the posterior tooth 34 has two cusps 5, 6 and the posterior tooth35 has three cusps, namely one buccal cusp 6 and two lingual cusps 5.The rest zone 11 of the posterior tooth 34 comprises a contact region 13in the distal masticatory-surface region, the top region 15 pointing inthe buccal direction. The posterior region 35 possesses a rest zone 11comprising four contact regions 13 arranged approximately in the shapeof a star, namely two smaller distally adjacent contact regions, whichbear by their base 16 in each case against the base 16 of two largercontact regions, the top region 15 of which is directed approximatelybuccally and lingually, respectively, and this also applies to the topregions 15 of the smaller contact regions 13. The large posterior teeth36, 37 possess buccally two approximately equal-sized cusps 6, or threedifferent-sized cusps, and lingually two equal-sized or different-sizedcusps 5. The rest zones 11 of both posterior teeth 36, 37 are arrangedapproximately in the tooth centre, the four contact regions 13 beingarranged approximately in the shape of a star and their longitudinalaxes X--X running obliquely with respect to the longitudinal fissure 7.

The rest zones 11 are each arranged approximately on the longitudinalaxis Z--Z of the teeth. That is to say the longitudinal fissure 7divides approximately centrically in each case the individual posteriorteeth 24 to 27 and 34 to 37 of the upper jaw and lower jaw,respectively. A uniform masticatory pressure on the longitudinal axis ofthe teeth is thereby achieved, the result of which is that the dynamicsduring mastication are improved and the periodontium is spared unduestress .

In the region of the premolars, the rest zones 11 have an extent both inthe longitudinal direction and in the transverse direction ofapproximately 0.17 cm and in the region of the molars they have amaximum extent in the longitudinal direction and in the transversedirection of approximately 0.24 cm.

Furthermore, it may also be expedient, according to the invention, ifthe rest zones 11 are formed in such a way that they extend over theentire region of the longitudinal fissures 7 in the individual teeth 24to 27 and 34 to 37. In this case, the occlusion-fixing cusps, i.e. thebuccal cusps 6 of the posterior teeth 34, 37 of the lower jaw and thepalatal cusps 5 of the posterior teeth 24 to 27 of the upper jaw, aresaddle-shaped in the region of their ridges.

A further expedient development of the invention, which is alsoindependent of the formation of the rest zones described in FIGS. 1 and2, consists in forming in the region of the respective longitudinalfissure 7 in the individual teeth 24 to 27 and 34 to 37; respectively,discharge grooves 12 which lead to the outside via the edge of the toothbody of the respective tooth. These discharge grooves 12 start, insofaras rest zones 11, according to the invenotion, are present, at thedeepest point of the respective rest zone 11. These discharge grooves 12are approximately V-shaped in cross-section and have in each case adepth of about 0.27 mm in the premolars 24, 25 and 34, 35 and a depth ofapproximately 0.40 mm in the molars 26, 27 and 36, 37. This depth ispresent in particular at the start of the discharge groove 12 in theregion of the rest zone. At the end of the discharge groove 12 in thewall region of the tooth body, the discharge groove 12 runs out at adepth "0". As is evident from FIGS. 1 and 2, in the case of the small.posterior teeth (premolars) 24, 25 arod 34, 35, respectively, in eachcase at least one discharge groove 12 is formed in such a way that itstarts in the respective rest zone 11 and runs out in the lingual andpalatal wall region of the tooth body, respectively, and in each caseone discharge groove 12 runs out of the longitudinal fissure 7 into thewall region of the two lateral surfaces. In the case of the largeposterior teeth (molars) 36, 37 and 26, 27, respectively, at least twodischarge grooves 12 are provided, one running out in thepalatal/lingual wall and the other in the buccal wall of the respectivetooth body, and in each case one discharge groove 12 runs out of thelongitudinal fissure 7 into the wall region of the two lateral surfaces.The discharge grooves 12 according to the invention ensure that the foodwhich is comminuted on the masticatory surfaces is forced out of themasticatory surface in the closed position of the teeth, so that themashed food is able to flow off and thus mutual adhesion of the teeth inthe region of their masticatory surfaces caused by the mashed food isavoided. Moreover, an accumulation of food is prevented and thusinstabilities are avoided.

It can be seen furthermore from FIGS. 1 and 2 that there is provisionaccording to the invention, and again independently of the formation ofthe rest zones 11 and the food discharge grooves 12, in each case forpositive-locking elements 22, 23 to be formed on the lateral surfaces20, 21 of the individual teeth, which positive-locking elements areshaped in such a way that respectively opposite positive-lockingelements of neighbouring teeth correspond in a positive-locking mannerwith one another, in particular with linear contact. Thepositive-locking elements may be convex projections of one tooth andcorrespondingly adapted concave indentations of the other tooth. As aresult, an interlocking of the teeth with one another is achieved. Bymeans of this interlocking, the teeth are aligned with respect to oneanother and at the same time are better supported against one another.

In FIG. 3 a buccal view of the teeth 24 to 27 is illustrated.

FIG. 4 shows the palatal view, associated with the buccal view accordingto FIG. 3, of the teeth 24 to 27. In these figures, identical toothportions to those in FIGS. 1 and 2 are given the same referencenumerals.

In FIG. 5 the lingual view of the teeth 34 to 37 is illustrated. FIG. 6shows the buccal view, associated therewith, of the teeth 34 to 37,identical tooth portions to those in FIG. 2 again being given the samereference numerals.

In FIG. 7 the lingual view in the closed position of the teeth 34 to 37and 24 to 27 is illustrated. Here, it can be seen that the teeth can bearranged in a so-called one-to-one tooth relationship. FIG. 8 likewiseshows the lingual view of the teeth 24 to 27 and 34 to 37, respectively,in the closed position. here, however, a so-called one-to-two toothrelationship is illustrated. By means of the design, according to theinvention, of the occlusal surfaces 1 to 4 of the small and largeposterior teeth, it is possible to construct both a one-to-one toothrelationship and a one-to-two tooth relationship.

We claim:
 1. A large and small artificial posterior tooth pair for thehuman upper and lower jaw, the occlusal surfaces of which comprise atleast one buccal cusp and at least one palatal cusp, between which alongitudinal fissure runs in the longitudinal direction of the tooth,where the buccal cusp of the lower jaw posterior tooth engages in thelongitudinal fissure of the upper jaw posterior tooth and the palatalprotuberance of the upper jaw posterior tooth engages in thelongitudinal fissure of the lower jaw posterior tooth, comprising:thelongitudinal fissures (7) and the palatal/lingual cusp (5) and thebuccal cusp (6) of the posterior teeth (34-37, 24-27) are coordinatedwith each other to form, in the region of the longitudinal fissures (7)that divide the side teeth (24-27, 34-37) approximately in the middle,at least one rest zone (11) in the median longitudinal axis (Z--Z) ofthe tooth, the rest zone having at least one contact region (13);supporting cusps of antagonist teeth of said pair lying on the at leastone contact region (13) with point contact of occlusal surfaces(1,2,3,4) in the closed position of the upper and lower jaws; and theremaining region of the occlusal surfaces (1,2,3,4) having no touchingcontact, thereby avoiding a stamping action and improving masticatoryproperties of the tooth pair.
 2. Artificial posterior tooth according toclaim 1, characterised by construction as a large posterior tooth (26,27) of the upper jaw, two rest zones (11) spaced in the longitudinaldirection of the posterior tooth (26, 27) being present, one beingformed in the distal region and the other in the mesial region. 3.Artificial posterior tooth according to claim 1 characterised byconstruction as a small posterior tooth (24, 25) of the upper jaw, onerest zone (11) being formed in the mesial region.
 4. Artificialposterior tooth according to claim 1, characterised by construction as alarge posterior tooth (36, 37) of the lower jaw, one rest zone (11)being formed approximately in the centre of the occlusal surface (3, 4).5. Artificial posterior tooth according to claim 1, characterised byconstruction as a small posterior tooth (34, 35) of the lower jaw, onerest zone (11) being provided in the distal region.
 6. Artificial toothaccording to claim 1, characterised in that the palatal/lingual cusps(5) and the buccal cusps (6) are convex-shaped and in particular have aflank angle of approximately 20 to 30'.
 7. Artificial posterior toothaccording to claim 1, characterised in that the rest zones (11) extendover the entire length of the longitudinal fissure (7) and theocclution-fixing palatal cusps (5) and the buccal cusps (6) aresaddle-roof-shaped in longitudinal section.
 8. Artificial posteriortooth according to claim 1, characterised in that an antistress regionis formed around the rest zone (11) for enlarging the said rest zone(11).
 9. Artificial tooth according to claim 1, characterised in thatthe rest zones (11) comprise at least one contact portion (13) having atorodal-shaped surface.
 10. Artificial posterior tooth, namely, a smallposterior tooth and a large posterior tooth for the upper and lower jawin humans, the occlusal surface of which has at least one buccal cuspand at least one palatal cusp, between which a longitudinal fissure runsin the longitudinal direction of the tooth, in particular according toclaim 1, characterised in that at least one food discharge groove (12)leads to the outside via the edge of the respective tooth body, startingfrom the longitudinal fissure (7).
 11. Artificial posterior toothaccording to claim 10, characterised in that the at least one fooddischarge groove (12) starts in the rest zones (11, at the deepest pointthereof.
 12. Artificial tooth according to claim 10, characterised inthat the at least one food discharge groove (12) is v-shaped in across-section and preferably has a depth of 0.5 to 0.7 mm at the startof the rest zone (11) and run out towards the end.
 13. Artificialposterior tooth, in particular a small or large posterior tooth for theupper jaw and lower jaw in humans, the occlusal surface of which has atleast one buccal cusp and at least one palatal cusp, between which alongitudinal fissure runs in the longitudinal direction of the tooth, inparticular according to claim 1, characterised in that positive-lockingelements (22, 23) are formed on the opposite lateral surfaces (20, 21)of the posterior teeth (24 to 27) and (34 to 37), respectively, whichpositive-locking elements correspond in a positive-locking manner withtheir respectively opposite positive-locking elements of theneighbouring tooth.
 14. Artificial posterior tooth according to claim13, characterised in that the positive-locking elements (22, 23) areconvex- and concave-shaped, respectively.